Not knowing much about your situation, here are some general tips that may or may not be useful. Also, recommending again Daniel Goleman's work for developing basic social literacy.

1) Be happy about the size of your social circle. Some people think they have to run out and make lots of friends as quickly as possible. I think it's better to hang out with the people you know and work on just having a good attitude. More friends (if that's really what you want) will happen of their own accord.

2) Relatedly, let things evolve naturally. It's better to be relatively hands-off, go with the flow and resist the temptation to manufcature new relationships/friendships/hobbies/social interactions.

3) Do things you like, regardless of where they take you socially. Some people think you can't go to a movie without friends. I think the opposite - you should be doing stuff you enjoy, without worrying too much about whether there are people doing it with you.

4) Then, look for opportunities to invite people to do stuff with you. If it's stuff you like doing anyway, you'll be more enjoyable to hang out with.

5) Be open to anything. People offer you chances to go do new things - dinner at their place, a concert, paintball - all the time. Take up the opportunities. If you're agreeable, eager, and ready to learn, people will love having you around.

6) Be faithful. Some people seem to have a bad habit of ditching old friends when new, cooler ones seem to be available - like now they have a chance to hang out with the cool kids, so they're going to get rid of those embarrassing old weirdos they were making do with for a while. Don't do this! It won't make you happy, it'll just make you a fake asshole. Staying true to your old friends, regardless of their quirks, is key to staying true to yourself, and very important if you are doing better socially and making friends. Remember your roots.

7) Say nice things. Just make an effort to say nice things, often. Compliment people on their clothes, taste in music, abilites, work they've done, house, whatever. You might think you're very complimentary but I think it can be surprising (if you're anything like me) how much people appreciate hearing you voice your approval aloud. People love it.

8) Use agreeable words like "yes," "sure," "okay," "awesome," and so on. Say "great" instead of "good." Say "great!!" instead of just "great." Just try consciously to change your language to use more positives. At first it might feel a bit weird but it makes a big difference, and it becomes more natural. You will just become a more positive person. (Did you notice that I tried to give as much of this advice in positives rather than negatives?)

9) Be yourself. Do you want to hang out with people right now or just be on your own? Do you what you want to do. Pay attention to your own feelings, and try and communicate what you are feeling clearly - while being respectful and considerate of course. Pay attention to your inner state.

10) Real importantly, it's okay if you don't click with everyone. Maybe what you're looking for is just two or three really close friends. If so, those are going to be people you can really, really relate to. Feeling comfortable with others starts with honesty. It's not about trying to act cool or super friendly, it's about being yourself around people you trust and who trust you. It's not always easy to find people who fit with you (and for whom you fit likewise) but it's worth it. The main thing is not to worry, with these things it can feel like nothing is changing and nothing will ever changes for aaaaaaages, then suddenly, overnight, it all just happens. It usually finally happens, I think, when you relax and forget to worry about it.

Hope that helps. Feel free to correct me if my advice doesn't map to your specifics. Otherwise, good luck : )